Air tube



Aug. 3, 1954 'r. F. JONES 2,685,306

. AIR TUBE Filed Dec. 9, 1950 IN V EN TOR.

I ATTOHNE Y5.

Patented Aug. 3, 1954 AIR TUBE Tillman F. Jones, Wichita, Kans.,assignor to The Coleman Company, Inc., Wichita, Kans., a corporation ofKansas Application December 9, 1950, Serial No. 200,038

3 Claims.

This invention relates to an air tube and to the method of forming thesame. The invention is particularly useful in connection with a pipeemployed for conveying heated air or conditioned air and in which thepipe is formed from sheet metal rolled into cylindrical shape.

In the manufacture of pipe commonly used with hot air systems, sheets ofmetal are rolled into cylindrical form and the edges of the metal arebent back and interlocked, the interlocked seam being usually swaged tosecure the edges of the pipe together. The resulting pipe is not trulyround and in securing the pipe sections together considerable difiicultyis often experienced in uniting the pipe sections, while often loose orunsatisfactory connections are made. Further, the pressure of theoutside pipe upon the enclosed pipe often causes an undesirable slippageof the parts near their connecting edges. There has long been a need fora pipe section which could be inexpensively formed while at the sametime providing an end having a true or uniform diameter which may bereadily secured and clamped within the other or expandable end of thesection. A substantial factor in the problem has been the requirementthat little cost can be added to the pipe because so much of the pipe isrequired for an installation and the cost of the pipe enters largelyinto the cost of the complete installation.

An object of the present invention is to provide a pipe structure whichovercomes the above disadvantages and permits ready assembly of thesections into a continuous pipe while preventing undesirable slippage ofthe interlocked edge portions of the sections. Yet another object is toprovide a method for inexpensively forming pipe sections which permitsthe sections to be readily connected while forming uniformly tightjoints. A still further object is to provide an air tube structure whichmay be formed quickly and at a minimum of cost While providing for theconnection of the tubes readily and in a manner permitting theoverlapping portions to be clamped tightly together. Other specificobjects, and advantages will appear as the specification proceeds.

The invention is shown in an illustrative embodiment, by theaccompanying drawing, in which- Figure l is a broken view in elevationof pipe sections embodying my invention, a portion of the structurebeing shown in section; Fig. 2, a broken top plan view; Fig. 3, an endview of a section; Fig. 4, a broken perspective View; and

Fig. 5, a detailed sectional view, the section being taken as indicatedat line 5-5 of Fig. 2.

In the illustration given, l0 designates a pipe section which is formedfrom a sheet of metal rolled into cylindrical form and provided withinterlocking edge portions H and t2, as illustrated in Fig. 5. At oneend of the pipe, the pipe edges are brought into simple overlappingrelation, as indicated at I3,,and that end of the pipe is adjusted bymeans of a jig so as to provide a slightly reduced end and the end issecured in this condition by a spotweld M or by other suitable means.

The lock seam [5 formed by the hooked edges II and I2 is preferablyloose, permitting movement to increase or decrease the over-alldiameter.

The end of the pipe opposite the seamed end is also provided with a slipseam in which one edge I6 ov laps the other edge I1. I prefer also toequip the latter or larger end of the pipe with a clamp [8 which haslaterally extending integral strap portions l9 welded at 20 to the pipeon opposite sides of the slip seam. The clamp 18 is formed of malleablemetal so that when the leg portions of the clamp are pressed towardseach other they draw the overlapping portions of the pipe inwardly overeach other and tighten the pipe about the enclosed pipe and the heavy ormalleable metal cap I8 holds the parts in this position.

In the specific illustration shown, I provide a standard 3 /2" 0. D. and28" length of pipe. It will be understood that any length may beemployed and the diameter of the pipe may be varied as desired. By meansof a jig and spotweld, the male end of the pipe is held to the properdimension and secured therein while the opposite end is givenflexibility by the use of the loose lock seam and by the slip seam atthe end of the pipe. It will be understood, however, that this structuremay be varied to give the desired flexibility.

Operation In the operation of the structure, a sheet metal strip isrolled upon itself to form the cylinder shown. The edges of the metalintermediate the pipe length are brought into interlocking position asillustrated at l l and I2. The ends of the pipe are provided with simpleoverlapping strips providing slip seams. The reduced end of the pipe isheld to a desired smaller diameter by the use of a jig, and that end ofthe pipe is secured by spotwelding against further change.

The other end of the pipe is provided with a clamp for utilizing theflexibility of that end for clamping that end of the pipe readily aboutthe reduced end of another pipe. Thus ready and accurate fitting isaccomplished when the pipes are joined, by simple compressing of theclamp 48. In this operation, the reduced end which is spotwelded at 14resists the compression caused by clamping the loose end of another pipeabout it while at the same time providing a sturdy base about which theclamping is efiected. As a result, the uniting of pipe ends isaccomplished easily and quickly, while at the same time permitting theends to be clamped tightly against each other without the slipping ofjoints and While thus providing a tight seal. The forming of the pipe isaccomplished at substantially no increased expense and in the resultingassembly of the pipe sections, a great saving in time and labor isbrought about.

While in the foregoing specification, I have set forth a singlestructure in considerable detail for the purpose of illustrating anembodiment of the invention, it will be understood that the details ofsuch structure and method may be varied widely by those skilled in theart without departing from the spirit of my invention.

1 claim:

1. An air tube, comprising a sheet of metal rolled into cylindrical formand provided intermediate its end portions with interlocking edgesforming a pipe, said pipe at one end thereof being provided withoverlapping portions providing a slip joint, and said end being reducedin diameter and spotwelded, the other end of said pipe being providedwith a loose line of division permitting tightening of the pipe, and aclamp member having integral stra portions secured to said pipe onopposite sides of said line of division for normally maintaining saidpipe end in enlarged condition for receiving the welded end of anotherpipe, said clamp being adapted to be compressed for tightening the looseend of the pipe about the reduced end of another pipe.

2. An air tube, comprising a sheet of metal rolled into cylindrical formand provided intermediate its end portions with interlocking edgesforming a pipe, said pipe at one end thereof being provided withoverlapping portions providing a slip joint, said end being reduced indiameter and rigidly secured, the other end of said pipe being providedwith a loose line of division permitting tightening of the pipe, and aclamp member having integral strap portions secured to said pipe onopposite sides of said line of division for normally maintaining saidpipe end in enlarged condition for receiving the reduced end or" anotherpipe, said clamp being adapted to be compressed for tightening the looseend of the pipe about the reduced end of another pipe.

3. In an air tube, a sheet of metal rolled into cylindrical form andprovided intermediate its end portions with interlocking edges forming apipe, said pipe at one end thereof being provided with overlappingportions providing a slip joint and said end being reduced in diameterand the overlapping portions secured together, the other end of saidpipe being'provided with a loose line of division for tightening of thepipe, and a clamp member secured to said pipe at the loose line ofdivision thereof for normally maintaining the pipe end in condition forreceiving the reduced end of a similar pipe, said clamp being adapted todraw the loose end of the pipe about the reduced end of another pipe.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 539,334 Barclay May 18, 1895 942,256 Hague Dec. '7, 19092,463,593 Boardman Mar. 8, 1949 2,483,412 Harker Oct. 4, 1949

